VOL-2112 move to voltha-lib-go

Change-Id: Ic1af08003c1d2c698c0cce371e64f47b47b8d875
diff --git a/vendor/github.com/DataDog/zstd/zstd.go b/vendor/github.com/DataDog/zstd/zstd.go
index e9953d6..b6af4eb 100644
--- a/vendor/github.com/DataDog/zstd/zstd.go
+++ b/vendor/github.com/DataDog/zstd/zstd.go
@@ -23,6 +23,7 @@
 	"bytes"
 	"errors"
 	"io/ioutil"
+	"runtime"
 	"unsafe"
 )
 
@@ -84,6 +85,7 @@
 		C.size_t(len(src)),
 		C.int(level))
 
+	runtime.KeepAlive(src)
 	written := int(cWritten)
 	// Check if the return is an Error code
 	if err := getError(written); err != nil {
@@ -107,6 +109,7 @@
 			C.uintptr_t(uintptr(unsafe.Pointer(&src[0]))),
 			C.size_t(len(src)))
 
+		runtime.KeepAlive(src)
 		written := int(cWritten)
 		// Check error
 		if err := getError(written); err != nil {
@@ -115,7 +118,7 @@
 		return dst[:written], nil
 	}
 
-	if dst == nil {
+	if len(dst) == 0 {
 		// Attempt to use zStd to determine decompressed size (may result in error or 0)
 		size := int(C.size_t(C.ZSTD_getDecompressedSize(unsafe.Pointer(&src[0]), C.size_t(len(src)))))